在R语言中基于另一数据框行号添加列的实现方法

基础R实现 #

首先需要将sites数据框中closest列的字符型行号转换为整数类型，之后直接通过行索引匹配stations中的站点名称：

# 原始数据定义
sites <- data.frame (name  = c("site_1", "site_2", "site_3","site_4"),
                     lat = c("49.99845", "58.30486", "55.70009","53.69490"),
                     long=c("-118.6791","-127.8108","-114.3307","-115.3906"),
                     closest=c("13","10","5","9")
)
stations<-data.frame(name=c("stationA","stationB","stationC","stationD",
                            "stationE","stationF","stationG","stationH","stationI","stationJ","stationK",
                            "stationL","stationM","stationN","stationO","stationP","stationQ"))

# 转换行号为整数并匹配站点名称
sites$closest <- as.integer(sites$closest)
sites$stationname <- stations$name[sites$closest]

# 查看结果
print(sites)

tidyverse/dplyr实现 #

如果你习惯使用tidyverse生态的工具，可以用dplyr的mutate函数完成同样操作：

library(dplyr)

sites <- sites %>%
  mutate(
    closest = as.integer(closest),
    stationname = stations$name[closest]
  )

说明 #

这两种方法都是向量化操作，不需要循环遍历，处理数千行数据的效率很高，完全无需人工核对。执行后sites会自动新增stationname列，对应closest行号指向的stations站点名称。

内容的提问来源于stack exchange，提问作者Camila Hurtado